This was my punishment for breaking an oath on the River Styx. Then, from somewhere above us, a voice yelled, ‘Hey, Bronze Butt!’ Over the Colossus’s head, a cloud of darkness formed like a cartoon dialogue bubble. Out of the shadows dropped a furry black monster dog – a hellhound – and astride his back was a young man with a glowing bronze sword. The weekend was here. Percy Jackson had arrived.